The present invention relates to a printing press with a plate making unit for performing plate making for a plate mounted on a plate cylinder in a printing unit.
Generally, when performing plate making for a plate, it is required to increase the efficiency of plate making operation and to eliminate the space where a plate making unit is to be installed. Hence, in recent years, a plate making unit independent of the printing press is not provided, but a plate making unit added to the printing press itself performs plate making directly on the printing press. More specifically, a plate before plate making is mounted on a plate cylinder in a printing unit, and the plate making unit is moved to abut its head against the plate cylinder. Subsequently, the plate cylinder is rotated, and simultaneously the head is moved in the axial direction of the plate cylinder, thereby performing plate making for the plate. When the plate is to be supplied/removed or maintenance is to be performed, the plate making unit is separated from the printing unit.
In the conventional printing press described above, the plate making unit is temporarily moved at a position separate from the printing unit in order to perform maintenance or the like, and is moved at a position where plate making is to be performed again after maintenance completion. When the plate making unit is moved after maintenance completion, the position of the head greatly depends on the positioning precision of the plate making unit with respect to the printing unit. Poor head positioning precision greatly affects plate making precision and printing precision.
When the plate making unit is provided to each of a plurality of printing units, poor positioning precision affects the register accuracy of each ink color. In this case, an operator must perform the complicated, skilled operation of adjusting the positions of the plate cylinders in the printing units for the purpose of registration. This increases the load of the operator and requires the long preparation time, thereby reducing the productivity.
It is an object of the present invention to provide a printing press in which the productivity is improved and the plate making precision and printing precision are improved.
In order to achieve the above object, according to the present invention, there is provided a printing press comprising a plate cylinder which is rotatably supported by a frame and has an outer surface on which a plate is mounted, a plate making unit supported to be movable between an operative position where plate making is performed and a wait position to escape from the operative position, at least one first engaging member fixed to one of the frame and the plate making unit, a first regulating member fixed to the other of the frame and the plate making unit to engage with the first engaging member, the first regulating member having a recess extending in an axial direction of the plate cylinder, a second engaging member fixed to one of the frame and the plate making unit, and a second regulating member fixed to the other of the frame and the plate making unit to engage with the second engaging member, the second regulating member having a recess extending in a vertical direction.